Home SCIENCE How Castle Bravo Works World’s Biggest Nuclear Bomb Ever Detonated

How Castle Bravo Works World’s Biggest Nuclear Bomb Ever Detonated


Castle Bravo was the first in a series of high-yield thermonuclear weapon design tests conducted by the United States at Bikini Atoll, Marshall Islands, as part of Operation Castle. Detonated on March 1, 1954, the device remains the most powerful nuclear device ever detonated by the United States and the first lithium-deuteride-fueled thermonuclear weapon tested using the Teller-Ulam design.

source.image: Learn from the base

Castle Bravo’s yield was 15 megatons of TNT. 2.5 times the predicted 6 Mt (25 PJ), due to unforeseen additional reactions involving lithium-7, which led to radioactive contamination in the surrounding area. Watch the video from Learn from the base for more info:

The Castle Bravo device was housed in a cylinder that weighed 23,500 pounds (10,700 kg) and measured 179.5 inches (456 cm) in length and 53.9 inches (137 cm) in diameter. The primary device was a COBRA deuterium-tritium gas-boosted atomic bomb made by Los Alamos Scientific Laboratory, a very compact MK 7 device.


This boosted fission device had been tested in the Upshot Knothole Climax event and yielded 61 kilotons of TNT. The assembled module weighed 1,840 lb (830 kg), measuring 30.5 in (770 mm) across. It was located at the end of the device, which, as seen in the declassified film, shows a small cone projecting from the ballistic case. This cone is the part of the paraboloid that was used to focus the radiation emanating from the primary into the secondary.